Until recently most carriers couldn't identify, much less improve the performance of networked applications--except to prescribe more bandwidth as a performance panacea. This is changing as distributed application delivery system (ADS) technologies mature and carriers and value-added network service providers respond to global enterprises' need for applications to perform well for all users, no matter where they are.

Products to optimize application performance over a wide area network (WAN) are fast becoming main stream. Global enterprises are now familiar with distributed ADS solutions from the likes of Cisco, Riverbed, Juniper and Packeteer--and as their familiarity increases, so does their penchant to purchase these solutions as managed services. Service providers like AT&T, BT Global Services, Orange Business Services, Swisscom, Telindus, Vanco, and Verizon Business are stepping up to the plate with sophisticated services to measure, control (i.e., protect from degrading under adverse network conditions), and accelerate (i.e., speed up for all users all the time) application performance.

To learn what application performance services are available and why customers are drawn to them, we interviewed five network service providers, each with an application optimization story to tell. Here is what we learned.

As for who is buying, the consistent answer is global enterprises. Application performance service buyers are primarily multinational companies tasked with delivering acceptable performance to corporate users in many global nooks and crannies. The challenge of delivering a quality experience to far-flung users is great to begin with, and it is often exacerbated by corporate initiatives like datacenter consolidation which extends the distance between servers and application users, thus increasing latency and further hurting the user experience.

The application performance problems that domestic U.S. enterprises experience tend not to be as profound as those of their multinational counterparts, which explains why the domestic U.S. carriers we approached during our research don't offer solutions beyond basic MPLS, and therefore receive no mention here.

As for why global enterprises buy performance services rather than "rolling their own" solutions, the answer is because it is easier and cheaper. The combined challenges of hiring and training employees, running gauntlets of import/export laws, and deploying, tuning and maintaining equipment in multiple countries make global self service difficult and expensive.

The question is can a carrier match the level of application performance management an enterprise can achieve in house? APM is difficult enough when an enterprise owns most of the assets that deliver the application. When the application delivery system is outsourced, good APM reporting by the service provider becomes paramount. This is challenging given APM complexity and the immaturity of application performance reporting by most equipment vendors.